American Journal of Epidemiology Advance Access originally published online on February 10, 2009
American Journal of Epidemiology 2009 169(6):693-703; doi:10.1093/aje/kwn400
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ORIGINAL CONTRIBUTIONS |
Heart Rate Variability, Ambient Particulate Matter Air Pollution, and Glucose Homeostasis: The Environmental Epidemiology of Arrhythmogenesis in the Women's Health Initiative
Correspondence to Dr. Eric A. Whitsel, Cardiovascular Disease Program, Departments of Epidemiology and Medicine, University of North Carolina at Chapel Hill, Bank of America Center, Suite 306-E, 137 East Franklin Street, Chapel Hill, NC 27514 (e-mail: ewhitsel{at}email.unc.edu).
Received for publication March 24, 2008. Accepted for publication December 3, 2008.
Metabolic neuropathophysiology underlying the prediabetic state may confer susceptibility to the adverse health effects of ambient particulate matter <10 µm in diameter (PM10). The authors therefore examined whether impaired glucose homeostasis modifies the effect of PM10 on heart rate variability in a stratified, random sample of 4,295 Women's Health Initiative clinical trial participants, among whom electrocardiograms and fasting blood draws were repeated at 3-year intervals from 1993 to 2004. In multilevel, mixed models weighted for sampling design and adjusted for clinical and environmental covariables, PM10 exposure was inversely associated with heart rate variability. Inverse PM10–heart rate variability associations were strongest for the root mean square of successive differences in normal-to-normal RR intervals (RMSSD). Among participants with impaired fasting glucose, there were –8.3% (95% confidence interval: –13.9, –2.4) versus –0.6% (95% confidence interval: –2.4, 1.3), –8.4% (95% confidence interval: –13.8, –2.7) versus –0.3% (95% confidence interval: –2.1, 1.6), and –4.3% (95% confidence interval: –9.4, 1.0) versus –0.8% (95% confidence interval: –2.7, 1.0) decreases in the RMSSD per 10-µg/m3 increase in PM10 at high versus low levels of insulin (P < 0.01), insulin resistance (P < 0.01), and glucose (P = 0.16), respectively. These associations were stronger among participants with diabetes and weaker among those without diabetes or impaired fasting glucose. The findings suggest that insulin and insulin resistance exacerbate the adverse effect of PM10 on cardiac autonomic control and thus risk of coronary heart disease among nondiabetic, postmenopausal women with impaired fasting glucose.
diabetes mellitus; glucose; heart rate; insulin; particulate matter
Abbreviations: HOMA-IR, insulin resistance according to homeostatic model assessment; PM10, particulate matter <10 µm in diameter; RMSSD, root mean square of successive differences in normal-to-normal RR intervals; SDNN, standard deviation of normal-to-normal RR intervals; WHI, Women's Health Initiative